Tow vehicle with anti-back up wheels

ABSTRACT

A tow vehicle adapted to be guided for movement along a slot is provided with swivel castor wheels at the front end of the vehicle. The front castor wheels are provided with roller clutch bearings which act as a brake to prevent the vehicle from being moved in a rearward direction.

United States Patefi Zetterlund Aug. 7, 1973 [54] TOW VEHICLE WITHANTll-BACK UP 3,528,534 9/1970 Benson et al. [88/8284 WHEELS 2,619,37011/1952 Leger 104/172 BT 3,094,944 6/1963 Bradt et al. 104/172 HTInventor: Stanley Zefierlund, Easwn, Pa. 3,119,347 l/1964 Dehne 104 172BT 3,427,992 2/1969 Jones et al..... 104/172 HT [73] As-slgnee- SIHandlmg sysiems Easton 3,589,301 6/1971 Reagan 104/172 BT 3,236,3372/1966 Marland et a1. 1811/8284 [22] Filed: Mar. 8, 1971 3,542,160 111970 Sacchini 188/82.84

[2]] Appl' 121637 Primary ExaminerDrayton E. Hoffman Att0meySeide1,Gonda & Goldhammer [52] U.S. Cl. 104/172 ET, 188/82.84 [51] Int. Cl.365g 17/42, F16d 63/00 57 ABSTRACT [58] Field of Search 104/172 BT;

188/82 84 A tow vehicle adapted to be gulded for movement along a slotis provided with swivel castor wheels at the [56] References Cited frontend of the vehicle. The front castor wheels are provided with rollerclutch bearings which act as 3 UNITED STATES PATENTS brake to preventthe vehicle from being moved in a R25,723 2/1965 Bradt et a1. 104/172 BTrearward di i 2,962,128 11/1960 Luenberger 188/82.84 3,436,994 4/1969Diener et al. 188/82.84 3 Claims, 4 Drawing Figures PATENTED B 7 7INVENTOR STANLEY L. ZETTERLU/VD BY wu,

JILL 28% @63 Z5? "Z2 MFMVM ATTORNEYS TOW VEHICLE WITH ANTI-BACK UPWHEELS The present invention is directed to a tow vehicle, and moreparticularly, to a tow vehicle having antiback up wheels. A large numberof tow vehicles have been proposed heretofore. Such vehicles areprovided with a tow pin or guide members which cooperate with a slot orsome other track to guide the vehicle as it is propelled along the slot.

Heretofore, tow vehicles of the type involved in the present inventionhave been provided with a brake means cooperating with the rear wheelsof the vehicle to prevent the vehicle from being moved in a rearwarddirection. A brake means for accomplishing this is needed in connectionwith tow vehicles so that the vehicle does not move rearwardly when itcontacts an obstruction. Also, it is often desirable to cause thevehicles to accumulate, that is, selectively lose contact with itspropelling means. When accumulating, a cart tends to recoil and rollbackwards. This will allow the bumper to disengage whereby the tow pinwill drop and reengage with the conveyor. This is prevented by thepresent invention. If accumulated vehicles are on a slight incline, theytend to roll rearwardly due to gravity and this is prevented by thepresent invention.

A wide variety of devices for applying a brake to the rear wheels of thetow vehicle has been proposed heretofore. For example, see U. S. Pat.Nos. 2,619,370; 3,427,992; 3,119,347; 3,094,944; and Re. 25,723. Inthese patents, a brake for the rear wheels is responsive to movement ofan accumulation bumper.

The present invention is directed to a vehicle which is provided with ananti-back up means, namely a means to prevent the vehicle from beingmoved rearwardly parallel to the main slot. However, the presentinvention accomplishes this in a novel manner which is substantiallyless expensive than those proposed heretofore. At the same time, thepresent invention eliminates maintenance needed to adjust the cables andrear brakes utilized heretofore. Further, the present inventioneliminates the need for a ledge on the rear of the vehicle, therebyenabling an accumulation bumper to be pivoted or hinged from aboverather than below. An accumulation bumper which is hinged from above iseasier to activate, requires less force to activate and lift the towpin, and can permit accumulation by contact with any obstacle.

In accordance with the present invention, the front wheels of thevehicle are swiveled castors. Each of the front wheels is provided withroller clutch bearings which only permit the front wheels to rotate inone direction, namely the direction whereby the vehicle will moveforwardly. The roller clutch bearings on the front wheel automaticallybrake the front wheels in the event that the vehicle is moved in arearward direction parallel to the main slot and one independent of anyaccumulation bumper.

It is an object of the present invention to provide a tow vehicle withbrake means to prevent the vehicle from moving in a rearward direction.

It is another object of the present invention to provide a tow vehiclehaving brake means to prevent the vehicle from moving in a rearwarddirection, with the brake means being part of the front swivel castors.

It is another object of the present invention to provide a tow vehiclewith brake means to prevent the vehicle from moving rearwardly, the samebeing accom plished in a manner which is inexpensive, reliable, andsubstantially reduces maintenance.

It is another object of the present invention to provide a tow vehiclewhich is provided with a brake means to prevent the vehicle from movingin a rearward direction while eliminating the need for a rear ledge andfacilitating the use of an accumulation bumper which is hinged at itsupper end.

Other objects will appear hereinafter.

For the purpose of illustrating the invention, there is shown in thedrawings a form which is presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

FIG. 1 is a perspective view ofa typical vehicle incorpoating thepresent invention.

FIG. 2 is a bottom plan view of the vehicle shown in FIG. 1, but on asmaller scale.

FIG. 3 is a sectional view taken through the bearing of a front castorwheel along line 3-3 in FIG. 2, but on an enlarged scale.

FIG. 4 is a side elevation view of the vehicle shown in FIG. 1.

Referring to the drawing in detail, wherein like numerals indicate likeelements, there is shown in FIG. 1 a tow vehicle in accordance with thepresent invention designated generally as It). The structural details ofthe vehicle 10, except for the front wheels, are conventional and willonly be referred to briefly.

The vehicle 10 includes a base 12 mounted on front swivel castor wheels14 and 15 and rear wheels 18 and 20. The vehicle 10 includes an uprightframe at the front end thereof supporting a vertically disposed tow pin22.

The tow pin 22 is adapted to enter the main slot 24 in a referencesurface such as floor 25. Tow pin 22 cooperates with the main slot 24for guiding the vehicle 10 therealong and at its lower end is adapted toengage a propelling means such as a conveyor. Contact between the towpin and the propelling means causes the vehicle it) to move along themain slot 24.

In large tow vehicle systems, it is often desirable or necessary tocause the vehicles 10 to accumulate. Accumulation involves causing thetow pin to lose contact with the propelling conveyor means. This may beaccomplished in a variety of ways. Most conventional tow vehicles causeaccumulation by utilizing an accumulation bumper which when moved willraise the tow pin 22 so that it is nolonger in contact with thepropelling conveyor means.

In a typical tow vehicle system, it is often desirable to cause thevehicle 10 to be transferred from movement along the main slot 24 tomovement along a shunt slot which intersects the main slot at an acuteangle. A typical shunt slot is identified by the numeral 34. The vehicle10 may be provided with means to cause the tow pin 22 to transfer frommovement along the main slot 24 to movement along the shunt slot 34.Such means may include selector rods 26 and 28 on the front end of thevehicle which are adapted to cooperate with abutments 30 and 32.

The vehicle 10 as described above is typical of a conventionalcommercially available vehicle and is described in greater detail in U.S. Pat. No. Re. 25,723. Hence, Further discussion of the details of thevehicle it) is not deemed necessary. It is emphasized that the vehicle10 as described above is merely illustrative of a wide variety of towvehicles which may incorporate the means for preventing the vehicle frommoving rearwardly in accordance with the present invention.

The truck wheels 14 and 16 are swivel castor wheels and may rotate abouta vertical axis from the solid-line position to the phantom positionshown in FIG. 2. Each of the front wheels 14 and 16 is identical.Accordingly, only wheel 16 will be described in detail.

As shown more clearly in FIG. 3, the inner rim 36 of the wheel 16 isspaced from the shaft 38. A brake means in the form of a roller clutchbearing designated generally as 40 is disposed in the gap between theinner periphery of rim 36 and the outer periphery of shaft 38. Theroller clutch bearing 40 is preferably force-fit to the ID of the rim36. If desired, the clutch 40 could be force-fit onto the shaft 38.

The roller bearing clutch 40 may include a cupshaped housing having anouter race 42 and an inner race 44 connected together by an end wall 46.Needle roller bearings 47 extend parallel to the axis of shaft 48. ifdesired, ball bearings could be used.

As the wheels 16 rotate in a direction whereby the vehicle moves in aforward direction, and counterclockwise in FIG. 3, the needle bearings47 move into the large space 50 while remaining in rolling contact withthe outer periphery of shaft 38. If the vehicle 10 is in any waysubjected to forces which tend to cause it to move in a rearwarddirection whereby-wheel 16 would rotate in the direction of arrow 48 inFIG. 3, the needle bearings 47 contact the inclined tapered surfaces 52and act as a brake. The shafts 38 on the wheels 14 and 16 do not rotate.

it is appreciated that roller clutch bearings, per se, have beenproposed heretofore and no claims to the bearings per se are madeherein. If the roller clutch bearings 40 were utilized on the rearwheels 18 and 20, the vehicle 10 would be difficult to utilize since thetow vehicle must be moved manually to and from the main slot 24. Bylocating the roller clutch bearing 40 on the front wheels, the vehicle10 may be manually moved by first applying a force in the direction ofarrow 54 in FIG. 2 to cause the wheels 14 and 16 to swivel to thephantom positions illustrated therein. Thereafter, the vehicle can bemoved in the direction of the wheels 14 and 16 so that it is possible toturn the vehicle around and facilitate manually moving the vehicle tothe main slot.

Thus, the use of roller bearing clutches for the front castor wheels ofan otherwise conventional truck solves the problem in a simple andreliable manner requiring virtually no maintenacne. Heretofore, thisproblem of vehicles accumulating behind other vehicles and then beingre-engaged with the conveyor chain were solved in one of two ways. Onemethod of solving this accumulation problem was to put a ledge on therear of the vehicle so as to hold the accumulation bumper on the nextadjacent vehicle up. Another method was to add exterior brakes tocooperate with the tread of the rear wheels and provide linkage wherebythe brakes were responsive to movement of the accumulation bumper.Frequently a combination of both said conventional methods has beenused.

Tow vehicles incorporating the anti-back up means in the front swivelcastor wheels are generally not visible. Hence, those persons skilled inthe art of tow vehicles when handling a vehicle in accordance with thepresent invention have been totally unaware that the vehicle includes ameans to prevent it from moving backwards along a main slot.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims, ratherthan to the foregoing specification as indicating the scope of theinvention.

I claim:

1. A tow vehicle for use in a tow system wherein a vehicle is mountedfor movement in the direction of a guide slot, said vehicle comprising abase, front and rear pairs of wheels supporting said base, said basehaving a guide means at the front end thereof for selective entry into aguide slot for guiding the base along the slot, said front pair ofwheels being mounted for swiveling movement with respect to a generallyvertical axis, said front wheels having brake means thereon forpreventing the front wheels from rotating in a direction to cause thebase to move rearwardly while the front and rear wheels are parallel toone another including rotatable clutch bearings surrounding thehorizontally disposed shafts about which the front wheels rotate, eachfront wheel brake means including inner and outer races force-fit to theinner periphery of the rim on the front wheels, said bearings beingcylindrical roller bear ings in said races parallel to the axis of thefront wheel shafts, the inner and outer races being constructed so as toenable the roller bearings to have a first position while the vehicle ismoving in a forward direction and a second position when the vehicle ismoving in a rearward direction, said outer bearing race having a taperedcam surface for preventing rotation of the roller bearings and frontwheels in the second position of said bearings.

2. A tow vehicle for use in a tow system wherein driverless vehicles aremounted for movement in the direction of a guided path, said vehiclecomprising a gener ally horizontal base, front and rear pairs of wheelssupporting said base, said front wheels being mounted for swivelingmovement with respect to a generally vertical axis, said front wheelshaving rotatable clutch bearings surrounding shafts of the front wheelsfor preventing the front wheels from rotating in a direction to causethe base to move rearwardly, each front wheel clutch bearing includinginner and outer races force-fit to the inner periphery of the rim of thefront wheels, roller bearings in said races parallel to the axis of thefront wheel shafts, the inner and outer races being constructed so as toenable the roller bearings to have a first position while the vehicle ismoving in a forward direction and a second position when the vehicle ismoving in a rearward direction, said outer bearing race having-a taperedcam surface for preventing rotation of the roller bearings and frontwheels in the second position of said bearings.

3. A vehicle in accordance with claim 2 wherein said brake means isautomatic and independent of the guide means and any bumper on the base.

1. A tow vehicle for use in a tow system wherein a vehicle is mountedfor movement in the direction of a guide slot, said vehicle comprising abase, front and rear pairs of wheels supporting said base, said basehaving a guide means at the front end thereof for selective entrY into aguide slot for guiding the base along the slot, said front pair ofwheels being mounted for swiveling movement with respect to a generallyvertical axis, said front wheels having brake means thereon forpreventing the front wheels from rotating in a direction to cause thebase to move rearwardly while the front and rear wheels are parallel toone another including rotatable clutch bearings surrounding thehorizontally disposed shafts about which the front wheels rotate, eachfront wheel brake means including inner and outer races force-fit to theinner periphery of the rim on the front wheels, said bearings beingcylindrical roller bearings in said races parallel to the axis of thefront wheel shafts, the inner and outer races being constructed so as toenable the roller bearings to have a first position while the vehicle ismoving in a forward direction and a second position when the vehicle ismoving in a rearward direction, said outer bearing race having a taperedcam surface for preventing rotation of the roller bearings and frontwheels in the second position of said bearings.
 2. A tow vehicle for usein a tow system wherein driverless vehicles are mounted for movement inthe direction of a guided path, said vehicle comprising a generallyhorizontal base, front and rear pairs of wheels supporting said base,said front wheels being mounted for swiveling movement with respect to agenerally vertical axis, said front wheels having rotatable clutchbearings surrounding shafts of the front wheels for preventing the frontwheels from rotating in a direction to cause the base to moverearwardly, each front wheel clutch bearing including inner and outerraces force-fit to the inner periphery of the rim of the front wheels,roller bearings in said races parallel to the axis of the front wheelshafts, the inner and outer races being constructed so as to enable theroller bearings to have a first position while the vehicle is moving ina forward direction and a second position when the vehicle is moving ina rearward direction, said outer bearing race having a tapered camsurface for preventing rotation of the roller bearings and front wheelsin the second position of said bearings.
 3. A vehicle in accordance withclaim 2 wherein said brake means is automatic and independent of theguide means and any bumper on the base.